A new appeal is set to be launched in the Scottish courts to attempt to clear the name of the convicted Lockerbie bomber, Abdelbaset al-Megrahi.

Campaigners, including Jim Swire, whose daughter died in the 1988 Pan Am bombing, say efforts to overturn Megrahi's 2001 conviction for the murder of 270 people will go ahead even after the terminally ill Libyan has died.

A book by a former member of Megrahi's legal team forced the Scottish justice secretary, Kenny MacAskill, to deny last week claims of a "nod and a wink" understanding, under which Megrahi dropped his appeal in exchange for his compassionate release and return to Libya.

Megrahi was convicted by a special court of three Scots judges who sat without a jury in Camp Zeist in the Netherlands, but John Ashton's book, Megrahi, You Are My Jury, quotes the Libyan as saying that he was framed, claiming that evidence seen by prosecutors was never passed to the defence. "There was a huge pressure to convict and it's clear now there was blatant intellectual dishonesty surrounding his trial," said Ashton. "Along with significant new forensic evidence, it's pretty clear this is an unsafe conviction."

Evidence not seen by the defence includes a break-in at Heathrow in the early hours of 21 December 1988, that could have allowed a device to be planted among security-screened Pan Am luggage. Doubts have also been cast over payments made to a key prosecution witness and a circuit board fragment found in the wreckage that prosecutors said was part of bomb timer made for Libyan authorities.